One of the great challenges in neuroscience is to understand how the neurons of the brain work together as a circuit to compute behaviors, and how such circuit functions are changed in brain disorder states. There is a great need for technologies that enable the neural activity of large numbers of individual cells to be measured in the brain of a mammal such as a mouse - ideally throughout the entire brain, since we do not precisely know the exact set of cells involved with any behavior or brain disorder. We here propose two radical departures from the past, using computational and theoretical analyses to design new neural recording devices, and augmenting these technologies with supplementary tools to enable the bridging of dynamic and anatomical pictures of the brain. As we validate these technologies, we will examine whole-brain neural dynamics and anatomical phenotypes in autism and schizophrenia mouse models, performing whole-brain activity mapping to characterize the altered computations associated with psychiatric illness. Such maps may fundamentally open up new frontiers in thinking about how distributed brain circuits are changed in mental illness, paving the way to new treatment strategies.